New leading single from a well loved artist, with a good pop sound, and a stale-from-ages Top ten, just CALLS for a fast rise and great radio+sales performance.
I am not surprised at all Pink's doing so well
In the incoming two weeks the chart will be shaken.
It should; it's rising at the convenient pace and the songs ahead of it are all decreasing after months up.
Pink is coming, but Katy will still benefit from sales, radio love and the fact Wide Awake is a really good song which is differently paced from all the rest on the Top charts lately.
I would be surprised if she wouldn't get at least a week on top.
I love Scream but a lot of L4M is much better than it. I really do think he needs to release the title track because I think it will make both old fans happy & give him new ones as well (more alternative-leaning listeners).
It's time for Scream to die, so this is a good time for it to fall out the Top 10.
Next horrid song to get kicked out is "Payphone". "Mercy" better take charge of it. 
Pink! 
sounds so good!
It's sold so poorly.